1. Field of the Invention
The present invention relates to a broadband wireless access system, and more particularly to a method for recognizing a connection state between a mobile station (MS) and a base station (BS), and a method and apparatus for quickly performing network re-entry when the mobile station (MS) moves out of a coverage area of the base station (BS).
2. Discussion of the Related Art
In a general mobile communication system, uplink (UL) data may not be unexpectedly received from a mobile station (MS) during a predetermined period of time, or a feedback signal (ACK or NACK signal) for downlink (DL) data may not be unexpectedly transmitted to a base station (BS).
In this case, the BS performs triggering of a resource retain timer, and stores context information of the MS during the triggering time, such that the MS can easily perform network re-entry. The aforementioned method is implicitly provided from a general mobile communication system. In reality, a specific time or reference at which the MS moves out of a network area (i.e., coverage area) is unclear, such that it is necessary for the BS must unnecessarily to store context information of the MS.
That is, in accordance with a general technology, if the MS moves out of a coverage zone of a serving BS (SBS), there is a difference in synchronization between the SBS and the MS. However, behaviors between the MS and the SBS are not definitely defined yet. In addition, the general or conventional technology does not provide a method for allowing the SBS to decide the presence or absence of a coverage loss of the MS.